1. Field of the Invention
The invention relates generally to molding machines, and more particularly to article handling apparatus for use with a molding machine.
2. Description of Prior Art
Mechanisms for extracting or unloading molded articles from a molding machine upon separation of male and female mold members are generally known in the art. With reference to U.S. Pat. No. 3,040,378, for example, a mechanism for unloading molded articles from a molding machine comprises a substantially rectangular frame which is reciprocally movable from a normal retracted position clear of the mold portions into and out of a space between the mold portions when open for collecting parts ejected by an ejecting mechanism. In the retracted position, the frame is tilted for dumping the molded articles into a collecting bin. Such an unloading mechanism has several disadvantages. First, the mechanism is cumbersome and is not capable of moving between its unloading and retracted positions very rapidly. As a consequence, the number of molded articles produced by such a molding machine in a given time interval is relatively low. Another disadvantage is that if any malfunction occurs in the mechanism used for synchronizing movement between the frame and mold portions, it is possible that the mold portions would close upon the frame thereby causing damage to the frame and/or mold portions.
In U.S. Pat. No. 3,910,740, an ejection control system for use with an injection molding machine is described. The molding machine comprises a pair of mold members movable between a mold-open and a mold-closed position. In the mold-closed position, the mold members define a plurality of mold cavities into which molten plastic is injected to form molded articles. The movable mold portion is provided with a stripper plate and a pair of vertical guide rails. The guide rails are transversely movable by a control mechanism which separates them during a mold closing stroke and drives them towards each other during a mold opening stroke. In operation, the molded article is formed in the mold cavity. The movable mold member then moves to the mold-open position with the molded article adhering thereto. As the movable mold member moves to the mold-open position, the guide rails move toward each other and to a position such that the guide rails bracket the molded article. The stripper plate engages a stop and strips the article from the movable mold member as it continues to its mold-open position, thereby allowing the molded article to descend along a path defined by the guide rails. An overhead blower is disclosed for facilitating and accelerating such descent.
Apparently, the interaction between the guide rails, stripper plate and at least the movable mold portion necessitates that these parts be closely synchronized within tight tolerances. Further, any time the mold members are moved to the mold open position for routine maintenance or repair, the guide rails will be in their operative position thus interfering with attempted maintenance. Still further, any flashing (unwanted small protrusions of plastic material from the molded article) that might form between the molded article and the stripper plate would tend to prevent the article from freely falling down the guide rails. Lastly, the stripper plate would be ineffective for stripping articles having the same outer dimension as the movable mold member, i.e., articles that do not have marginal edges extending laterally outwardly from the movable mold member.